Why there is no Subscription to onContactsDataProviderErrorSignal event in OHContactDataSource

[ajaybeniwal]

In all examples we are firing onContactsDataProviderErrorSignal on dataproviders, but there is no subscription to this event in the OHContactDataSource file , so currently it is very difficult to catch NSError from api calls in view controllers. So want to ask how to catch NSError events in viewcontroller using onContactsDataProviderErrorSignal , documentation lacks how to handle errors gracefully if we are loading contacts from remote datasource

[NickEntin]

Hi Ajay, the data source itself doesn't handle errors from the data providers. Instead, you should add your view controller as the observer for the onContactsDataProviderErrorSignal on each of the data providers you are using. So, in your view controller class, you will have something along the lines of:

// Initialize the data provider.
let dataProvider = OHCNContactsDataProvider(delegate: self)

// Add the error handler.
dataProvider.onContactsDataProviderErrorSignal.addObserver(self, callback: { (error, dataProvider) in
    // Handle the error.
})

// Initialize the data source.
let dataSource = OHContactsDataSource(dataProviders: NSOrderedSet(objects: dataProvider), postProcessors: NSOrderedSet())

dataSource.onContactsDataProviderFinishedLoadingSignal.addObserver(self, callback: { (contacts) in
    // Everything was successful.
})

// Load the contacts from the data provider into the data source.
dataSource.loadContacts()